April 2023 saw a clandestine gathering in South Korea’s bustling capital, Seoul, where senior officials convened for the first meeting of the Forum for Nuclear Strategy. The discussion centred on the contentious topic of South Korea’s nuclear ambitions, an idea that has shifted from a fringe one to a dominant trend in recent years, driven by various factors. This paper aims to delve into and examine these factors, particularly in light of the fact that over 70% of South Koreans now support their country becoming a nuclear power.
In fact, this is not South Korea’s first foray into nuclear weapon development. The initial efforts date back to the 1970s, which were halted when the United States intervened, offering Seoul a choice: continue with its nuclear ambitions or rely on the US nuclear arsenal for protection. South Korea opted for the latter, adhering to this decision for decades. However, recent security and geopolitical shifts on the global stage have prompted a reevaluation of this stance.
In this context, state think tanks in South Korea have highlighted the urgent need for Seoul to pursue nuclear armament, particularly in light of Russia’s suspicious efforts to strengthen ties with North Korea, potentially culminating in the Russia-North Korea defense pact. Additionally, there is a growing belief in South Korea that the credibility of America’s deterrence strategy is waning in the face of developments in the Indo-Pacific region.
I. What Is the United States’ Extended Deterrence Strategy?
The Extended Deterrence Strategy (EDS) commits the United States to using its military power, including its nuclear arsenal, to protect the security of its allies, notably South Korea, Japan, and Taiwan. This strategy was adopted by the United States in the aftermath of World War II as part of the emerging new world order.
Over the years, the EDS has been put to the test, but it now faces destabilizing pressures from the anti-American camp and their allies. They argue that the United States has failed to provide sufficient reassurances about the EDS’s effectiveness amid significant shifts in the international landscape and growing nuclear ambitions among US allies in the South China Sea region. This situation demands that the United States re-evaluate and potentially redesign the EDS to enhance its effectiveness. This may include creating a more dynamic integration of nuclear and conventional weapons and restructuring alliances to bolster the EDS’s impact.
In this regard, the United States should take action in two main directions. The first is extended deterrence, targeting adversaries with the intent of sending deterrent messages to prevent attacks. The second concerns assurances, directed towards allies, to provide reassuring messages that affirm the United States’ role as their protector and guarantor. Together, these strategies create a mental image in the minds of both adversaries and allies about the credibility of the United States in providing deterrence and protection.
Indeed, reassuring allies is inherently more challenging than deterring adversaries because allies are unwilling to take any risks with their security, necessitating constant reassurance. In contrast, the deterrence strategy the United States has employed since World War II hinges on the implied threat of force to convince adversaries that the costs of attacking or invading a neighbor would far outweigh any potential gains. Deterrence becomes particularly powerful when wielded by states with nuclear military capabilities.
Donald Trump’s ascent to power in 2017 sparked a genuine crisis for America’s allies due to his harsh criticism of these alliances. This led to a significant erosion of trust among these countries regarding the United States’ commitment to their security, forcing them to seek alternatives. This was exemplified by Vietnam, which proceeded to sign eleven agreements with Russia, including one involving nuclear technology transfer, highlighting the risk of nuclear militarization in the Indo-Pacific region.
At times, the strategy of deterrence or guarantees can drive some countries to preemptively attack their adversaries, realizing too late that they lack actual US protection, or provoke their enemies into launching an attack, as in the situation with Taiwan. However, there are no concrete indications that the United States has entirely lost its deterrent capability, as evidenced by the fact that no country has withdrawn from the Nuclear Non-Proliferation Treaty.
The deterrence strategy in the Indo-Pacific region is especially crucial due to the region’s sensitivity and the prevailing tensions, largely driven by China’s ambitions to dominate the South China Sea and monopolize its resources. Consequently, the United States’ EDS in the Indo-Pacific is more effective here than in any other part of the world. Washington’s capabilities in the region range from conventional military power to nuclear capabilities, aimed at addressing the security challenges posed by China. Among the 32 treaties the United States has signed globally to support its EDS—most within NATO—there are key bilateral defense agreements with non-NATO countries, including South Korea, Japan, the Philippines, Taiwan, Thailand, and Australia.
In the current geostrategic landscape, alternative deterrence methods like economic sanctions have largely failed to sway adversaries, as evidenced by the cases of Russia, Iran, and North Korea. This underscores the continued importance of traditional means, such as conventional and nuclear weapons, in any deterrence strategy and predicts the growing nuclear ambitions of many countries.
II. Russian-North Korean Cooperation
North Korea’s nuclear capabilities are the primary catalyst driving Seoul to consider developing its own military nuclear force. Recent escalations by Pyongyang have heightened tensions, particularly following the signing of a Russia-North Korea defense pact, which has raised concerns about the potential threats if either country is attacked. Further fueling these fears, Russian President Vladimir Putin has openly acknowledged North Korea’s nuclear status, defying all UN Security Council sanctions and potentially prompting other nations, particularly China, to follow suit. A South Korean government research center study suggested that Seoul should explore diversifying its options, including reconsidering the deployment of tactical nuclear weapons.
In the same vein, North Korea’s unofficial nuclear status significantly fuels nuclear ambitions in the Indo-Pacific region. Pyongyang’s steadfast refusal to engage in denuclearization talks with the United States casts doubt on the credibility of the US nuclear deterrent umbrella. Compounding this uncertainty is North Korea’s nuclear doctrine, which relies on the concept of pre-emptive strikes, heightening regional tensions.
From another perspective, Russia’s involvement exacerbates concerns about Pyongyang supplying Moscow with weapons for use in Ukraine, driven by the depletion of Russian ammunition stocks. Consequently, the assistance Moscow has provided to North Korea, including assistance with a successful satellite launch after previous failures, appears to be in exchange for securing weapons rather than Pyongyang seeking protection from Russia. This situation heightens the risk of a third world war, particularly after the United States and Europe have supplied Ukraine with offensive weapons and permitted their use against targets inside Russia.
III. Chinese Practices in the South China Sea and the Case of Vietnam
Chinese actions in the South China Sea are just as significant in fueling nuclear ambitions in the Indo-Pacific region, particularly given the waning credibility of the United States and its deterrent capabilities. For instance, Beijing has managed to stir concerns on the Japanese side about the disputed islands through a combination of civil and military measures, albeit on a limited scale, as well as diplomatic maneuvers.
The decline in US credibility in the Indo-Pacific can only be mitigated through targeted measures that prioritize strengthening security alliances with major regional countries such as Indonesia, the Philippines, and Malaysia. This is particularly crucial given Russia’s recent involvement, including signing eleven agreements with Vietnam, one of which involves the transfer of nuclear technology. If anything, this development highlights the missed opportunity for the United States to secure such agreements in advance, especially since Vietnam is a significant economic player in the region.
Several key factors highlight Vietnam’s significance in the region, starting with the US Seventh Fleet presence off its shores and the fact that 30% of global trade flows through its territorial waters. Additionally, Vietnam-along with the Philippines, Malaysia, Brunei, and Indonesia-holds substantial wealth in the South China Sea. This may explain why the United States maintains its largest military deployment outside its borders in the Pacific Ocean, which China refers to as the South China Sea.
On the other hand, there are disputes between China and Vietnam in the South China Sea and over borders, among other issues. The United States aims to leverage Vietnam to deter China from invading Taiwan, while Russia is currently seeking to use Vietnam to support China and distance Hanoi from the United States. Amid its conflicts with China, Vietnam has made several attempts to explore gas and oil in the South China Sea, but Beijing has consistently blocked these efforts. Despite US efforts to form an alliance including Vietnam, Taiwan, South Korea, and Japan to weaken China’s regional influence, these attempts have faltered. Russia’s role as a mediator has proven effective in distancing South China Sea countries, particularly Vietnam, from the United States by arming these countries and even facilitating the localization of nuclear technology.
A second key factor for the United States to leverage in its Indo-Pacific security alliances is the development of allies’ nuclear capabilities to equal those of its adversaries. The third factor involves the imperative of ongoing consultations with US allies in the Indo-Pacific and the creation of advisory mechanisms akin to those connecting the United States with NATO. This would bolster allies’ confidence by involving them in strategic decision-making processes that ensure their protection.
Overall, Chinese actions reveal that Beijing’s ambitions extend beyond invading Taiwan or controlling the South China Sea. China perceives the global system as inherently flawed and in need of restructuring based on new principles, including its relations with neighbors, international powers, and its nuclear capabilities—a domain shrouded in considerable non-transparency, according to international assessments. Nonetheless, the continuous expansion of Beijing’s nuclear arsenal provides it with the flexibility to adapt its strategy to virtually any changes or emergencies.
IV. Cooperation between the United States and South Korea
In recent years, particularly following the Russian-Ukrainian war, numerous challenges to the United States and its influence have surfaced, posing a threat to Washington’s alliances. This situation necessitated an expansion of the US deterrence strategy, as the diminishing credibility of US deterrence could strongly motivate both South Korea and Japan to develop their own nuclear capabilities. Amid shifting dynamics and the rise of political, military, and technological factors threatening decades-old strategic balances, countries may transition from extended deterrence to extended nuclear deterrence. This strategy, consistently emphasized by the United States, ensures that the US nuclear deterrent remains both credible and flexible.
Relatedly, the South Korean President proposed last year that Seoul might need to consider acquiring its own nuclear weapons to address challenges in a deteriorating security environment. This line of thought is concerning because it will not be limited to South Korea. Both Japan and Australia are considering the pursuit of military nuclear technology to face threats, with Japan being especially explicit about its aspirations. Former Japanese Defence Minister Shigeru Ishiba stated in 2017 that “Japan should possess the capability to build nuclear weapons.” Additionally, it should be noted that these countries are technically capable of developing nuclear weapons and that restrictive political considerations are no longer relevant and may not act as impediments to nuclear proliferation but rather as catalysts for it.
Following the Russia-North Korea defense pact, concerns grew in South Korea about the possibility of this cooperation bolstering Pyongyang’s nuclear capabilities. This led to the urgent deployment of a US aircraft carrier to South Korean waters to conduct military exercises aimed at warning North Korea. South Korea also summoned the Russian ambassador to voice its protest against Moscow’s joint defense agreement with Pyongyang.
In this context, South Korea is proactively seeking to renew its agreement with the United States to station over 28,000 American soldiers on its soil to deter any attack from North Korea. This move is driven by concerns that a potential return of Trump to power could complicate the renewal process, even though the current agreement is valid until the end of 2025.
On the other hand, discussions between the United States and South Korea include plans to integrate nuclear operations’ simulations into their joint military exercises next year. In this vein, the South Korea-US Nuclear Consultative Group has been established. However, there is a cautious approach to developing this relationship to avoid giving Pyongyang the impression that these measures extend beyond deterrence to direct threats of force. As a result, the two countries have agreed to delay the transfer of the United Nations Joint Forces Command from the United States to South Korea.
Yet, South Korea’s nuclear ambitions encounter significant hurdles. For instance, during the 70th anniversary of the US-South Korea Mutual Defense Treaty last year, the presidents of both countries signed a declaration in which Seoul reaffirmed its commitment not to pursue nuclear weapons, while Washington renewed its pledge to provide a protective umbrella. The United States is handling this matter with care, enforcing stricter criteria for South Korea’s nuclear ambitions.
In short, the surge in nuclear ambitions across the Indo-Pacific is impossible to overlook, signaling a need for the United States to adapt its EDS to align with the shifting geopolitical landscape. Since 2012, the region has been a strategic focal point for US defense policies under the “rebalance to Asia” strategy introduced by former President Barack Obama. With both China and North Korea—one officially a recognized nuclear power and the other not—posing nuclear threats, the United States faces a challenge to its vital allies, Japan and South Korea. This situation necessitates that the United States enhance its efforts to reassure these allies, not only to protect existing alliances but also to prevent further nuclear proliferation.
